Pipe Joint Compounds Made for Gas Pipe Systems
When working with gas pipes, using the proper pipe joint compound is crucial for creating safe, leak-free connections.
What is Pipe Joint Compound?
Pipe joint compound, sometimes called pipe dope, is a unique sealant used on threaded pipe connections. It serves two main purposes - lubricating the threads to make tightening easier, and sealing the joint to prevent leaks. It has a smooth, doughy texture and is applied to the male threads before assembling the joint.
For gases like natural gas or propane, special pipe joint compounds are required that are rated for gas service. Regular thread sealants designed for water pipes are not adequate for sealing gas connections. Gas pipe joint compounds contain inert fillers that provide resistance to natural gas, propane, butane, hydrogen, and manufactured gases.
Key Differences from Standard Pipe Dope
There are a few key differences between standard pipe dopes and gas-rated joint compounds:
- Thicker consistency to fill thread gaps
- Non-drying/non-hardening to maintain seal
- Contains no VOCs or solvents
- Prevents galvanic corrosion
- Withstands vibration and temperature fluctuations
- Lab-tested for gas service
Gas service compounds are rigorously tested to gas industry standards for safe, durable seals. Products not specifically rated for gas use pose safety risks if used improperly.
Key Properties of Gas Pipe Joint Compounds
When selecting a pipe joint compound for gas pipes, there are a few key properties to look for:
- Non-hardening - it should maintain a pliable seal indefinitely
- Hydrocarbon resistance - won't react with propane, natural gas, etc.
- Low volatile organic compounds (VOCs) - minimal odor
- Non-corrosive - won't react with metal pipes or fittings
- Stable seal - remains effective despite vibration, temperature changes, etc.
- Good resistance to water, ammonia, and diluted acids
- NSF/ANSI Standard 61 certified for potable water & gas service
Gas pipe joint compounds are thicker than standard pipe dopes to ensure an airtight seal between pipe threads. They are also non-hardening so they will remain pliable over time.
How Gas Pipe Joint Compounds Create a Seal
Gas pipe dopes seal threads through a combination of factors:
- Fills microscopic voids between threads
- Adheres to all mating surfaces
- Forms a gasket at the joint interface
- Compensates for imperfections in thread fit
- Prevents vibration loosening
This allows the compound to continue sealing even if pipes shift slightly over time. The pliability also compensates for thermal expansion and contraction of pipes.
Types of Gas Pipe Joint Compounds
There are a few main types of pipe joint compound intended for gas line use:
PTFE Pipe Dope
PTFE (Polytetrafluoroethylene) pipe dopes use PTFE resin as the main sealing component. This resin-based compound offers superior chemical resistance for all types of gases. It withstands high temperatures up to 500degF but may harden over time.
RectorSeal Pipe Thread Sealant
RectorSeal No. 5 is a popular pipe thread sealant made from vegetable oil, inert fillers, and stabilizing additives. It has low VOCs, won't corrode pipes, and remains pliable. It's NSF/ANSI 61 certified for potable water and gas service.
Hybrid Pipe Joint Compounds
Some hybrid pipe dopes combine PTFE with other non-hardening fillers like calcium carbonate, silica, and kaolin clay. This provides added durability and viscosity for gas service.
Multi-Purpose Pipe Joint Compounds
Some multi-purpose, non-hardening pipe dopes are suitable for gas connections if they meet local code approval. Always verify NSF 61 certification and gas service rating before using.
Choosing the Right Compound
To pick the ideal pipe joint compound for your gas piping project, consider these factors:
- Pipe material - plastic, black iron, galvanized, etc.
- Gas type - natural gas, liquid propane, anhydrous ammonia
- Pipe size - diameter and thread count
- Project location - indoor vs. outdoor, buried or exposed
- Expected pressures - maximum system pressure
- Temperature range - peak hot and cold temps
- Local plumbing codes - product certifications required
Match the proper pipe dope viscosity and composition to the specific pipe material used. Plastic and non-ferrous pipes often need more sealant than steel. Check product ratings for your application.
Consult manufacturer specifications to match the proper pipe dope product to your specific application details. Using the right formulation will ensure consistent, long-lasting seals on all threaded gas connections.
Applying Pipe Joint Compound
To use pipe joint compound correctly on gas pipes:
- Clean threads - remove dirt, oil, grit with wire brush
- Apply compound evenly to male threads - cover all threads
- Assemble joint hand tight - thread together carefully
- Tighten with wrench - per manufacturer torque specs
- Wipe away excess compound - don't allow clogs
- Conduct pressure test - check for leaks before system use
The compound should make 2-3 threads visible past the fitting edge. Too little dope risks leaks, but too much can cause clogged gas lines.
Application Tips
- Avoid over-tightening joints
- Reapply sealant after disassembly
- Ensure proper curing time before pressure testing
- Always use within the product's working time
- Regularly inspect joints for leaks/voids
Following the usage guidelines carefully will ensure the pipe joint compound seals effectively.
Top Gas Pipe Joint Compound Brands
Some of the top-rated pipe joint compound manufacturers for gas service include:
- Oatey - Great White Pipe Joint Compound
- RectorSeal - No. 5 Thread Sealant
- Blue Monster - PTFE Thread Sealant Tape
- Loctite - 55 Pipe Thread Sealant
- La-Co - Slic-Tite Sealant
Compare product certifications, performance ratings, price, availability, and support when choosing a brand. Buying from a reputable manufacturer ensures optimal results.
Beyond pipe dopes, some other gas pipe sealant options include:
- PTFE tape - simple option but less effective
- Liquid sealants - fast-drying but lower viscosity
- Anaerobic adhesives - permanent seals for non-reuse
- Metal gaskets - reusable but require flanged fittings